ACCELERATOR

The present invention concerns an improved safety mechanism for the 5 return to rest position of a device, in particular an accelerator.

More particularly, the invention relates to the type of mechanism said above which provides a safety redundancy, by means of the provision of a primary spring and a secondary spring, with the secondary spring entering into action only in the event of breakage of the primary spring.

10 As it is known, in the design and manufacture of driving aids for disabled people, in particular as regards the management of the acceleration of a car, the designer must frequently face and solve the problem of ensuring the return to zero of the device in every circumstance, in particular of the accelerator.

15 In other words, the accelerator or other device implemented by the user must automatically return to the rest condition as the driver exerts less pressure on the command.

It is also known that the accelerator's return to the rest condition is usually carried out by at least one spring.

20 Said springs are normally loaded during the action carried out by the user (for example the action of acceleration), for example by means of a compression or extension during the movement performed by the responsible command (pedal command, or manual command, realised through various linkages).

25 A problem the designer of this type of device must face is related to the need to ensure, in the event of breakage of the spring or springs, the return to the rest position of the accelerator command or other device, as if the spring had integral conditions (i.e. in the absence of cracks or structural yielding of the spring or springs).

30 Moreover, recently legislation has been introduced in some countries which requires that such a solution is provided obligatorily; if it is not provided, the device will fail to be approved by the competent authorities.

In order to solve this problem, the provision of two springs has been proposed (redundancy of the return mechanism in the rest position of the 35 device), which work in parallel, so that if one breaks, the other guarantees the user at least the possibility of reaching the repair shop to restore the integrity of the mechanism.

However, as it is quite evident, this solution only in part responds to what is required, since the two springs are in any case each subject to the work cycles, therefore the spring that remains intact could also break quickly, for the same reasons that led to the breakage of the first.

In light of the above, the need is quite evident to have a mechanism that ensures operation without interruption of the device on which it is applied, by means of a redundant system that, during the operation of the primary mechanism, was not subject to ageing, and can therefore ensure durability to the user which is at least comparable to that of the primary mechanism. Another result which would be optimal to obtain is that of a mechanism which, in relation to that which is indicated in the previous paragraph, allows the user to be informed of the breakage of the primary mechanism, so as to be able to reach a repair shop, without hurrying, for the restoration of the system's integrity.

These and other results are obtained according to the present invention by means of a safety mechanism that provides the use of two identical springs, each independently capable of guaranteeing the correct return of the device (for example the acceleration command) in the rest position, in the times and modes requested, and which allows only one of the two springs to be operational, while the second one is non-operational as long as the first is in operation, and enters into action without interruption when the first breaks.

Therefore a specific object of the present invention is a safety mechanism for the return to rest position of a device, in particular an accelerator, said mechanism envisaging a primary spring, having a first end coupled to a first anchoring element and a second end coupled to a first tie-rod element, said first tie-rod element being coupled to a first crank of the primary spring, said first crank being integral with a housing of a shaft of the device on which said safety mechanism is provided, said first anchoring element being housed in a seat formed inside containment means, a secondary spring, normally at rest, having a first end coupled to a second anchoring element and a second end coupled to a second tie- rod element, said second tie-rod element being coupled to a second crank of the secondary spring, said second crank having an axis coinciding with the axis of rotation of said shaft and of said housing, and being provided with abutment means, to become integral with said first crank of the primary spring in the event of failure of the latter and of the entry into operation of the secondary spring, interference means between said first anchoring element and said second anchoring element , such as to keep the first anchoring element in position when said primary spring is in operation, and such to allow the same to move away from the first crank of the primary spring in case the latter breaks, and, in this case, to allow the block of the second anchoring element - secondary spring - second tie-rod - second crank to become integral with said shaft and said housing, such that the secondary spring becomes operational, the mechanism also comprising means for transferring motion to the device on which it is mounted.

In particular, according to the invention, an outer container is provided in said safety mechanism.

Preferably, according to the invention, said second anchoring element protrudes from said container when said secondary spring becomes operational.

Still according to the invention, said device is a manual accelerator.

Furthermore, according to the invention, said means for transferring motion to the device consist of a potentiometer or other position sensor, a complex of transfers and pulleys, or Bowden cables.

Still according to the invention, said interference means are constituted by a pin, or by one or more balls.

The present invention will now be described, for non-limiting illustrative purposes, according to its preferred embodiments, with particular reference to the figures of the attached drawings, wherein:

figure 1 is a first schematic perspective view of an embodiment of the mechanism according to the invention with some parts removed;

figure 2 is a second schematic perspective view of the embodiment of figure 1 with some parts removed;

figure 3 is a schematic view from above of the embodiment of figure 1 , with some parts removed and in a rest position;

figure 4 is a schematic perspective view of the mechanism according to the invention in the position of maximum acceleration;

figure 5 is a schematic view from above of the mechanism in the position of figure 4;

figure 6 is a schematic view from above of the mechanism according to the invention in the case of breakage of the primary spring;

figure 7 is a perspective view of the mechanism according to the invention in the case of breakage of the primary spring; figure 8 is a schematic view from above of the mechanism according to the invention in the case of action of the secondary spring;

figure 9 is a perspective view of the mechanism according to the invention in the case of action of the secondary spring;

figure 10 is a schematic view from above of the mechanism according to the invention in the case of action of the secondary spring in rest position; figure 1 1 is a perspective view of the mechanism according to the invention in the case of action of the secondary spring in rest position; and figure 12 is a broken, perspective view of the mechanism according to the preceding figures.

Referring to figures 1 , 2 and 12 of the drawings, a first embodiment of the mechanism according to the invention is shown applied to an accelerator, but it is quite evident to a person skilled in the art how it can be applied to any type of device which provides implementation by a user and a return to the rest position when the user does not act on the device.

In the figures, reference number 1 indicates a containment box, reference number 2 indicates a primary spring, reference number 3 indicates a secondary spring, reference number 4 indicates a housing of the acceleration shaft, reference number 5 indicates a potentiometer, reference number 6 indicates an acceleration rack, reference number 7 indicates an activation pin, reference number 8 indicates an anchoring element of the primary spring 2, reference number 9 indicates a tie-rod of the primary spring 2, reference number 10 indicates an anchoring element of the secondary spring 3, reference number 1 1 indicates a tie-rod of the secondary spring 3, reference number 12 indicates a crank of the primary spring 2, reference number 13 indicates a crank of the secondary spring 3, and reference number 14 indicates a containment cap.

As it can be seen, the mechanism according to the invention provides an acceleration shaft (not shown) that can rotate between an initial rest position, or, in the specific case, a position of non-acceleration, and a position of maximum extension or acceleration.

The figures only show the housing 4 of the acceleration shaft, which rotates integrally with the same.

The acceleration shaft also determines the integral rotation of the rack 6 and the crank 12 of the primary spring 2.

When the acceleration shaft rotates, the rack 6 integral with the same moves the gear of the potentiometer 5, such to be able to transmit the variation of acceleration to an electronic control unit. Obviously, the transmission of the variation of acceleration could be transmitted to a subsystem of pulleys and/or mechanical gears and/or Bowden cables that mechanically move the pedal of the original accelerator of the cars, without this being considered outside the scope of protection of the present patent application.

Also, in place of the potentiometer it is possible to provide a generic position sensor.

In the case of zero acceleration (rest position), the primary spring 2 is kept in pre-load condition, being fixed at one end to the anchoring element 8 and at the other end to the tie-rod 9.

The anchoring element 8 is housed in the containment box 1. The tie-rod 9 is constrained to the crank 12, which, as said, is integral in rotation with the acceleration shaft and the relative housing 4.

The secondary spring 3 is normally kept in load condition, being fixed at one end to the anchoring element 10 and at the other end to the tie-rod 1 1. The tie-rod 1 1 is constrained to the crank 13, which can rotate freely (idle) and independently around the axis of the acceleration shaft and its housing 4.

The tie-rod 1 1 is constrained and forced into its position, by the activation pin 7, housed in a hole (not shown) formed in the anchoring element 10 of the secondary spring 3. The pin 7 is maintained in this position due to the pressure exerted by the troncoconical profile of the anchoring element 8, which is in contact in a seat (not shown).

In case of the application of an external force (for example by the driver), the acceleration shaft is made to rotate, and with it the housing 4, the crank 12 of the primary spring 2 and the rack 6.

The potentiometer 5 detects the variation of the accelerator, and the primary spring 2 is loaded between the end fixed to the anchoring element 8, stationary, and the tie-rod 9, which instead moves, being integral with the crank 12.

The rotation of the acceleration shaft and its housing 4, does not cause any movement of the secondary spring 3, by virtue of the fact that the crank 13 is "idle" with respect to the housing 4.

In the event of a partial or total release of the accelerator, the primary spring 2 returns to its initial position, by imparting a rotation to the housing 4 in the opposite direction to that of acceleration, thus reducing the acceleration up to returning to the rest position.

During the acceleration phase, and hence the extension of the primary spring 2, the primary spring 2 could break.

In this case, occurring in real time, due to the absence of traction and to the thrust of the pin 7, the anchoring element 8 leaves its previous position (distant from the seat formed inside the containment box 1 ) and stops in abutment on the containment cap 14.

The pin 7 can now exit the seat formed in the anchoring element 10, following the troncoconical profile of the anchoring element 8, freeing the tie-rod 1 1 , which can thus move freely inside the anchoring element 8 (see in particular figure 6).

The tie-rod 1 1 is then actuated by the recall of the secondary spring 3, causing the rotation of the crank 13, up to causing the same to rotate up to filling the space that was provided with respect to the crank 12. See in particular figure 7.

Now the two cranks 12 and 13 always move integrally, rotating in synchronism around the axis of the acceleration shaft.

Thus, in the case of acceleration, with external force applied in such a way as to rotate the acceleration shaft and its housing 4, the crank 12 of the primary spring 2 rotates, causing the rotation, in its same direction, of the crank 13 of the secondary spring 3, extending and thus loading the secondary spring 2 (see in particular figures 8 and 9).

In this situation, in the case of partial or total release of the accelerator, the secondary spring 3 shortens, imparting a rotation in the opposite direction to the crank 13, which leads the crank 12 of the primary spring 2 and puts it in rotation, integral with the housing 4, thus reducing the acceleration up to cancelling it (see in particular figures 10 and 1 1 ).

The new condition of zero acceleration provides that the tie-rod 11 of the secondary spring 1 1 , exits outside the containment box 1 , sliding inside a suitable hole formed in the anchoring element 10. This changed geometry of the system can be used to unequivocally indicate that the primary spring 2 is broken, and the system is operating with the secondary spring 3. Said signalling can simply be of a visual type, or coupled to an electronic sensor to activate a malfunction light or similar.

The present invention has been described for non-limiting illustrative purposes, according to its preferred embodiments, but it is to be considered that any variations and/or modifications may be made by an expert in the field without departing from the relative scope of protection, as defined by the appended claims.